Patent GB-774088-A (GB)
Title: Starter control system
IPC: F02C7/277
Filed: 1953-10-27
Abstract: 774,088. Gas turbine plant. BENDIX AVIATION CORPORATION. Oct. 27, 1953 [Dec. 31, 1952], No. 29686/53. Addition to 774,087. Class 110 (3). [Also in Group XI] An engine starter comprising a turbine powered by burning a mixture of fuel and compressed air has electrically-operated air and fuel control means which are initially energized by a starter switch and a second electric circuit energized by pressure-responsive means responsive to the combustion chamber pressure to take over the energization of the air and fuel control means when the combustion chamber pressure reaches a predetermined value and to deenergize the system when the pressure falls below the predetermined value. The turbine 2 connected through reduction gearing 3 to a starter jaw 4 is supplied with working fluid by a combustion chamber 5. A compressed air bottle 7 is connected to the combustion chamber 5 through a conduit 8, pressure reducing solenoid operative valve 9, conduit 10, pressureresponsive valve 11, conduit 12 and nozzle 13. The air bottle 7 is also connected to a fuel accumulator 14 through a conduit 20, pressure reducer 21 and conduit 22. The fuel accumulator, which is connected to the combustion chamber 5 through a conduit 15 solenoidoperated valve 16 and conduit 17, is divided by an elastic diaphragm 26 into an air section 25 and a fuel section 24. The fuel section is also connected to the aircraft fuel system through a conduit 29 and a check valve 28. When it is desired to start the turbine starter, the switch 35 is closed and the control winding 47 of the relay 48 energized. The relay then actuates the switch arms 50, 51. The switch arm 50 closes the circuit of the solenoid-operated valves 9, 16, which are then opened, and energizes the spark coil 57. Air then passes from the bottle 7 to the space 25 and forces fuel from the space 24 through the valve 16 into the combustion chamber 5. At the same time air from the conduit 22 opens the valve 11 and allows air to flow from the bottle 7 to the combustion chamber 5. When the pressure in the combustion chamber reaches a predetermined value the pressure-operated switch 30 is actuated. Switch arms 31, 32 engage the contacts 33, 34 and thereby by-pass the switch 35 and energize the winding 65 which actuates the switch member 41 into engagement with the contact 67, thus rendering the switch 35 ineffective. When all the fuel in the chamber 24 has been burnt the combustion chamber pressure will fall and the switch 30 will return to the open position, relay 48 will be de-energized and the circuits of the solenoid-operated valves 9, 16 opened. The valves 9, 16 will then return to the closed position. When the valve 9 is in the closed position the conduits 10, 20 are vented to atmosphere. The valve 11 will then close and the accumulator will be refilled from the aircraft fuel system through the conduit 29 and valve 28. The solenoid-operated valves 9, 16 and spark coil 57 may be arranged in series instead of in parallel as shown. A centrifugal switch 44 is opened when the turbine exceeds a predetermined speed to de-energize the relay 48 and so de-energize the valves 9, 16 and spark coil 57.